Skip to content

Cleanup should_implement_trait lint code #15804

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 6, 2025
+69 −84
Merged

Cleanup should_implement_trait lint code #15804

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
153 changes: 69 additions & 84 deletions clippy_lints/src/methods/should_implement_trait.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::{is_bool, sym};
use rustc_abi::ExternAbi;
use rustc_hir as hir;
use rustc_hir::{FnSig, ImplItem};
use rustc_hir::{self as hir, FnRetTy, FnSig, GenericParamKind, ImplItem, LifetimeParamKind};
use rustc_lint::LateContext;
use rustc_middle::ty::Ty;
use rustc_span::edition::Edition::{self, Edition2015, Edition2021};
Expand All @@ -20,51 +19,43 @@ pub(super) fn check_impl_item<'tcx>(
sig: &FnSig<'_>,
) {
// if this impl block implements a trait, lint in trait definition instead
if !impl_implements_trait && cx.effective_visibilities.is_exported(impl_item.owner_id.def_id) {
if !impl_implements_trait && cx.effective_visibilities.is_exported(impl_item.owner_id.def_id)
// check missing trait implementations
for method_config in &TRAIT_METHODS {
if impl_item.ident.name == method_config.method_name
&& sig.decl.inputs.len() == method_config.param_count
&& method_config.output_type.matches(&sig.decl.output)
// in case there is no first arg, since we already have checked the number of arguments
// it's should be always true
&& first_arg_ty_opt
.is_none_or(|first_arg_ty| method_config.self_kind.matches(cx, self_ty, first_arg_ty))
&& fn_header_equals(method_config.fn_header, sig.header)
&& method_config.lifetime_param_cond(impl_item)
&& method_config.in_prelude_since <= cx.tcx.sess.edition()
{
span_lint_and_help(
cx,
SHOULD_IMPLEMENT_TRAIT,
impl_item.span,
format!(
"method `{}` can be confused for the standard trait method `{}::{}`",
method_config.method_name, method_config.trait_name, method_config.method_name
),
None,
format!(
"consider implementing the trait `{}` or choosing a less ambiguous method name",
method_config.trait_name
),
);
}
}
&& let Some(method_config) = TRAIT_METHODS.iter().find(|case| case.method_name == impl_item.ident.name)
&& sig.decl.inputs.len() == method_config.param_count
&& method_config.output_type.matches(&sig.decl.output)
// in case there is no first arg, since we already have checked the number of arguments
// it's should be always true
&& first_arg_ty_opt
.is_none_or(|first_arg_ty| method_config.self_kind.matches(cx, self_ty, first_arg_ty))
&& sig.header.is_safe()
&& !sig.header.is_const()
&& !sig.header.is_async()
&& sig.header.abi == ExternAbi::Rust
&& method_config.lifetime_param_cond(impl_item)
&& method_config.in_prelude_since <= cx.tcx.sess.edition()
{
span_lint_and_help(
cx,
SHOULD_IMPLEMENT_TRAIT,
impl_item.span,
format!(
"method `{}` can be confused for the standard trait method `{}::{}`",
method_config.method_name, method_config.trait_name, method_config.method_name
),
None,
format!(
"consider implementing the trait `{}` or choosing a less ambiguous method name",
method_config.trait_name
),
);
}
}

const FN_HEADER: hir::FnHeader = hir::FnHeader {
safety: hir::HeaderSafety::Normal(hir::Safety::Safe),
constness: hir::Constness::NotConst,
asyncness: hir::IsAsync::NotAsync,
abi: ExternAbi::Rust,
};

struct ShouldImplTraitCase {
trait_name: &'static str,
method_name: Symbol,
param_count: usize,
fn_header: hir::FnHeader,
// implicit self kind expected (none, self, &self, ...)
self_kind: SelfKind,
// checks against the output type
Expand All @@ -73,13 +64,12 @@ struct ShouldImplTraitCase {
lint_explicit_lifetime: bool,
in_prelude_since: Edition,
}

impl ShouldImplTraitCase {
#[expect(clippy::too_many_arguments)]
const fn new(
trait_name: &'static str,
method_name: Symbol,
param_count: usize,
fn_header: hir::FnHeader,
self_kind: SelfKind,
output_type: OutType,
lint_explicit_lifetime: bool,
Expand All @@ -89,7 +79,6 @@ impl ShouldImplTraitCase {
trait_name,
method_name,
param_count,
fn_header,
self_kind,
output_type,
lint_explicit_lifetime,
Expand All @@ -102,8 +91,8 @@ impl ShouldImplTraitCase {
|| !impl_item.generics.params.iter().any(|p| {
matches!(
p.kind,
hir::GenericParamKind::Lifetime {
kind: hir::LifetimeParamKind::Explicit
GenericParamKind::Lifetime {
kind: LifetimeParamKind::Explicit
}
)
})
Expand All @@ -112,36 +101,36 @@ impl ShouldImplTraitCase {

#[rustfmt::skip]
const TRAIT_METHODS: [ShouldImplTraitCase; 30] = [
ShouldImplTraitCase::new("std::ops::Add", sym::add, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::convert::AsMut", sym::as_mut, 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::convert::AsRef", sym::as_ref, 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitAnd", sym::bitand, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitOr", sym::bitor, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitXor", sym::bitxor, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::borrow::Borrow", sym::borrow, 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::borrow::BorrowMut", sym::borrow_mut, 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::clone::Clone", sym::clone, 1, FN_HEADER, SelfKind::Ref, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::cmp::Ord", sym::cmp, 2, FN_HEADER, SelfKind::Ref, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::default::Default", kw::Default, 0, FN_HEADER, SelfKind::No, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Deref", sym::deref, 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::DerefMut", sym::deref_mut, 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Div", sym::div, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Drop", sym::drop, 1, FN_HEADER, SelfKind::RefMut, OutType::Unit, true, Edition2015),
ShouldImplTraitCase::new("std::cmp::PartialEq", sym::eq, 2, FN_HEADER, SelfKind::Ref, OutType::Bool, true, Edition2015),
ShouldImplTraitCase::new("std::iter::FromIterator", sym::from_iter, 1, FN_HEADER, SelfKind::No, OutType::Any, true, Edition2021),
ShouldImplTraitCase::new("std::str::FromStr", sym::from_str, 1, FN_HEADER, SelfKind::No, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::hash::Hash", sym::hash, 2, FN_HEADER, SelfKind::Ref, OutType::Unit, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Index", sym::index, 2, FN_HEADER, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::IndexMut", sym::index_mut, 2, FN_HEADER, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::iter::IntoIterator", sym::into_iter, 1, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Mul", sym::mul, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Neg", sym::neg, 1, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::iter::Iterator", sym::next, 1, FN_HEADER, SelfKind::RefMut, OutType::Any, false, Edition2015),
ShouldImplTraitCase::new("std::ops::Not", sym::not, 1, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Rem", sym::rem, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Shl", sym::shl, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Shr", sym::shr, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Sub", sym::sub, 2, FN_HEADER, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Add", sym::add, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::convert::AsMut", sym::as_mut, 1, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::convert::AsRef", sym::as_ref, 1, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitAnd", sym::bitand, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitOr", sym::bitor, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::BitXor", sym::bitxor, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::borrow::Borrow", sym::borrow, 1, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::borrow::BorrowMut", sym::borrow_mut, 1, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::clone::Clone", sym::clone, 1, SelfKind::Ref, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::cmp::Ord", sym::cmp, 2, SelfKind::Ref, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::default::Default", kw::Default, 0, SelfKind::No, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Deref", sym::deref, 1, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::DerefMut", sym::deref_mut, 1, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Div", sym::div, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Drop", sym::drop, 1, SelfKind::RefMut, OutType::Unit, true, Edition2015),
ShouldImplTraitCase::new("std::cmp::PartialEq", sym::eq, 2, SelfKind::Ref, OutType::Bool, true, Edition2015),
ShouldImplTraitCase::new("std::iter::FromIterator", sym::from_iter, 1, SelfKind::No, OutType::Any, true, Edition2021),
ShouldImplTraitCase::new("std::str::FromStr", sym::from_str, 1, SelfKind::No, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::hash::Hash", sym::hash, 2, SelfKind::Ref, OutType::Unit, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Index", sym::index, 2, SelfKind::Ref, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::ops::IndexMut", sym::index_mut, 2, SelfKind::RefMut, OutType::Ref, true, Edition2015),
ShouldImplTraitCase::new("std::iter::IntoIterator", sym::into_iter, 1, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Mul", sym::mul, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Neg", sym::neg, 1, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::iter::Iterator", sym::next, 1, SelfKind::RefMut, OutType::Any, false, Edition2015),
ShouldImplTraitCase::new("std::ops::Not", sym::not, 1, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Rem", sym::rem, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Shl", sym::shl, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Shr", sym::shr, 2, SelfKind::Value, OutType::Any, true, Edition2015),
ShouldImplTraitCase::new("std::ops::Sub", sym::sub, 2, SelfKind::Value, OutType::Any, true, Edition2015),
];

#[derive(Clone, Copy)]
Expand All @@ -153,19 +142,15 @@ enum OutType {
}

impl OutType {
fn matches(self, ty: &hir::FnRetTy<'_>) -> bool {
fn matches(self, ty: &FnRetTy<'_>) -> bool {
let is_unit = |ty: &hir::Ty<'_>| matches!(ty.kind, hir::TyKind::Tup(&[]));
match (self, ty) {
(Self::Unit, &hir::FnRetTy::DefaultReturn(_)) => true,
(Self::Unit, &hir::FnRetTy::Return(ty)) if is_unit(ty) => true,
(Self::Bool, &hir::FnRetTy::Return(ty)) if is_bool(ty) => true,
(Self::Any, &hir::FnRetTy::Return(ty)) if !is_unit(ty) => true,
(Self::Ref, &hir::FnRetTy::Return(ty)) => matches!(ty.kind, hir::TyKind::Ref(_, _)),
(Self::Unit, &FnRetTy::DefaultReturn(_)) => true,
(Self::Unit, &FnRetTy::Return(ty)) if is_unit(ty) => true,
(Self::Bool, &FnRetTy::Return(ty)) if is_bool(ty) => true,
(Self::Any, &FnRetTy::Return(ty)) if !is_unit(ty) => true,
(Self::Ref, &FnRetTy::Return(ty)) => matches!(ty.kind, hir::TyKind::Ref(_, _)),
_ => false,
}
}
}

fn fn_header_equals(expected: hir::FnHeader, actual: hir::FnHeader) -> bool {
expected.constness == actual.constness && expected.safety == actual.safety && expected.asyncness == actual.asyncness
}